Motor vehicles are increasingly being fitted with systems for monitoring and/or measuring parameters, comprising sensors mounted on said vehicle.
By way of example of such systems, mention may be made of the monitoring systems that comprise electronic casings mounted on each of the wheels of vehicles, these being dedicated to measuring parameters, such as pressure and/or temperature of the tires with which these wheels are fitted, and intended to inform the driver of any abnormal variation in the measured parameter.
One of the current solutions most commonly used for attaching the electronic casings to the wheel rims is to make electronic units each made up of an electronic casing and of an inflation valve assembled with said electronic casing, that allows the latter to be secured to the rim of the wheel.
In addition, each electronic casing then conventionally comprises an external “eyelet”, and each inflation valve comprises a body intended to extend through the eyelet and through an orifice made in the rim, and an assembly head separated from the body by a shoulder that constitutes a face via which the eyelet and said inflation valve are immobilized against said rim.
Such a design makes it possible to obtain a tightening torque that is capable of correctly retaining the electronic casings in spite of the significant loadings (centrifugal force, vibrations, accelerations . . . ) to which these casings are subjected.
However, during the operations of mounting the tire on the rim of the wheel of the vehicle and removing it therefrom, the tire passes over the electronic casing and the rigid connection between the valve and the electronic casing breaks under the stress loadings applied by said tire.
As a result, it is necessary to be able to press the electronic casing firmly against the bottom of the rim so as to create contact between said casing and said rim so as to be able to withstand the forces applied by the tire during the operations of fitting same on and removing same from the rim, and thereby avoid breaking the electronic unit at the rigid connection between the electronic casing and the valve.
In order to ensure this contact between the electronic casing and the bottom of the rim′, electronic units have been proposed that comprise an electronic casing and a valve that are configured in such a way as to be able to adapt to the angular orientation between the electronic casing and the valve so that said electronic casing can be pressed firmly against the bottom of the rim, regardless of the profile and dimensions of said rim, before the electronic unit is fixed to the rim.
In general, in order to achieve this orientable angular connection, the electronic casing and the valve of the electronic unit comprise connecting elements of complementing shapes so as to generate a pivot connection. The valve is then inserted into the valve hole provided in the rim, then the electronic casing is rotated about the pivot connection. The angular orientation obtained in order to achieve contact between the electronic casing and the bottom of the rim is then blocked in position by friction as a nut is tightened, allowing the electronic unit to be fixed rigidly to the rim.
For example, document FR 2 907 048, incorporated herein by reference, describes an electronic unit for measuring operating parameters of a vehicle wheel, comprising an electronic casing and an inflation valve for securing said electronic casing to a wheel rim, comprising a body intended to extend through an orifice formed in the rim, and an assembly head separated from the body by a shoulder that constitutes a face via which said inflation valve is immobilized against said rim. The electronic casing comprises an exterior wall defining a lateral housing for the inflation valve assembly head, delimited by a metal plate made as one piece with said electronic casing, against which the immobilizing face of said assembly head bears, and provided with a cutout for the passage of the body of said inflation valve.
The metal plate and the immobilizing face of the assembly head have cylindrical contacting faces, allowing the inclination of the electronic casing with respect to the longitudinal axis of the inflation valve to be adjusted before the latter is immobilized against the rim. Such an articulation makes it possible to adjust the position of the electronic casings to suit the profiles of the rims, notably with a view to keeping said electronic casings in contact with the bottom of the rim and thereby to limiting the loadings experienced.
However, this solution has a number of disadvantages.
Specifically, when mounting the electronic unit on the rim, the operator therefore has to orient the electronic casing with respect to the valve until he achieves contact between the casing and the bottom of the rim, and keep said casing in contact with the rim while tightening the nut, something which is a complicated maneuver which does not make it possible to guarantee the desired contact.
In addition, this solution proves expensive because, in addition to the high price of the inflation valves, which are generally all-metal, it entails the production of ancillary components (nuts, seals, . . . ) which are especially designed to ensure this angularly adaptable connection.